Adult female hip bone density reflects teenage sports-exercise patterns but not teenage calcium intake.

OBJECTIVE: To examine how cumulative teenage sports histories and time-averaged teenage calcium intake are related to total body bone mineral gain between ages 12 and 18 years and to proximal femur bone mineral density (BMD) at age 18 years. Design. Longitudinal. Setting. University Hospital and local suburban community in Central Pennsylvania. STUDY PARTICIPANTS: Eighty-one white females in the ongoing Penn State Young Women's Health Study. OUTCOME MEASURES: Total body and proximal femur (hip) bone measurements by dual energy radiograph absorptiometry; nutrient intakes, including calcium, from 33 days of prospective food records collected at regular intervals between ages 12 and 18 years; and self-reported sports-exercise scores between ages 12 and 18 years. RESULTS: Cumulative sports-exercise scores between ages 12 and 18 years were associated with hip BMD at age 18 years (r = .42) but were not related to total body bone mineral gain. Time-averaged daily calcium intake, which ranged from 500 to 1500 mg/day in this cohort was not associated with hip BMD at age 18 years, or with total body bone mineral gain at age 12 through 18 years. CONCLUSIONS: The amount of physical activity that distinguishes a primarily sedentary teenager from one who engages in some form of exercise on a nearly daily basis is related to a significant increase in peak hip BMD.

Bone status among postmenopausal women with different habitual caffeine intakes: a longitudinal investigation.

OBJECTIVE: Caffeine consumption has been proposed as a risk factor for bone loss in postmenopausal women. Past epidemiologic studies on caffeine and bone have been confounded by covariates including cigarette and alcohol use, differing levels of physical activity and hormone replacement therapy. The purpose of the study was to use a longitudinal design to determine the relationship between habitual dietary caffeine intake and postmenopausal bone status. METHODS: Data were collected at two time points separated by two years; 138 women with little or no exposure to tobacco or to drugs known to affect bone status were seen at Visit 1, and 112 returned for Visit 2. Ninety-two of these subjects had received no drugs known to affect bone status over the two-year interval and were kept in the sample. Nutrient and caffeine intake were assessed from three-day diet records. Bone measurements were made by dual energy x-ray absorptiometry (DXA). RESULTS: Correlation analyses indicated no association between dietary caffeine intake and total body or femoral neck bone density or bone mass. Similarly, no associations were found between caffeine consumption and longitudinal changes in total body or femoral neck bone measurements. These results held true both with and without statistical adjustment for calcium intake. CONCLUSIONS: This study does not support the idea that caffeine is a risk factor for bone loss in healthy postmenopausal women.

Longitudinal nutrient intake patterns of US adolescent women: the Penn State Young Women's Health Study.

PURPOSE: To use longitudinal nutrient intake data to determine whether dietary patterns remain consistent (or "track") as U.S. females progress from age 12 to 18 years. METHODS: Three-day diet records were collected at regular intervals over 6 years from participants in the Penn State Young Women's Health Study. Eighty-one subjects remained in the cohort during the study period. Tracking in body weight, in dietary intake of fat, sugar, iron, vitamin C, and in a total dietary score (TDS) was assessed using quartile-ranking analysis, year-to-year Pearson correlation analysis, and longitudinal linear analysis. RESULTS: Rank analysis revealed that subjects maintained their relative quartile positions for body weight throughout the study period, and year-to-year correlation coefficients for this variable were .93-.94. In contrast, rank and correlation analyses showed that the subjects did not track strongly with respect to any nutrient variable. Age 12 to 18 years correlation coefficients ranged from r = .04 for fat intake to r = .15 for the TDS. In longitudinal linear models, slopes differed in direction and significance across the original quartiles for nutrient intake, indicating varying dietary trends over time within the study population. CONCLUSIONS: Nutrient intake patterns do not track strongly throughout adolescence among U.S. females.